The present invention relates to a back monitoring apparatus for a vehicle, and more particularly to a back monitoring apparatus for a vehicle for displaying a predicted path of the vehicle according to a steering angle when the vehicle is backed up in such a manner that it is superposed on a back image on a monitor.
In recent years, a back monitoring apparatus for confirming the back of a vehicle has become prevalent. The feature of a back monitoring apparatus resides in that it permits a vehicle driver to confirm the back (environment) easily in such a manner that the blind spot of a rearview mirror is monitored by a video camera. This feature is efficient the case where the environment of a direct back corner of the vehicle is hidden from view by a cabin as in a truck. Some back monitor apparatus not only displays a back image for a driver, but also displays a predicted path locus of a rear wheel according to a steering angle when the vehicle is backed up which is superposed on the image on a monitor, thereby improving the operability of a driver. An example of these monitoring apparatus is disclosed in JPA64-14700.
The display of the predicted path locus of the rear wheel disclosed in the above prior art permits the moving direction and vehicle width of one""s own vehicle to be visually recognized at first sight. Therefore, the driver can easily back up the vehicle for parking. However, as shown in FIG. 11, in backing-up of the vehicle, when a vehicle 100 is turned clockwise rearwards, a front wheel 101a located outside of the turning turns widely unlike the path of a rear wheel 102a corresponding to it. Therefore, when the driver is plunged into the operation of driving carefully viewing only the interior of the predicted path lines of the rear wheels 102a and 102b, a front body 100a which turns more widely than the rear wheel 102a may be brought into contact with an obstacle 103.
An object of the present invention is to provide a back monitor which can improve the safety confirmation and operation by a driver when a vehicle is backed up, by displaying a predicted path locus with excellent visibility in order to display a predicted path of the vehicle according to a steering angle when the vehicle is backed up in such a manner that it is superposed on a back image picked up by a video camera on a monitor.
In order to attain the above object, in accordance with the present invention, there is provided a back monitoring apparatus for a vehicle comprising:
a predicted path locus computing means for computing a predicted path locus of a vehicle corresponding to a steering angle when the vehicle is backed up;
a signal processing means for processing the predicted path locus so as to be superposed on a back image picked up by an image pick-up means; and
a monitoring means for displaying an image from the data thus superposed,
wherein the predicted path locus computing means computes predicted path loci of a minimum cornering portion and a maximum cornering portion of the vehicle,
the signal processing means processes the predicted path loci of the minimum cornering portion and the maximum cornering portion so as to be superposed on data of the back image; and
the monitoring means simultaneously displays the predicted path loci of the minimum cornering portion and the maximum cornering portion superposed the back image, which are supplied from the signal processing means.
In this configuration, since the predicted path loci of the minimum cornering portion and the maximum cornering portion superposed on the back image are simultaneously displayed, the predicted path direction of the vehicle and vehicle width can be known so that the back confirmation and operability by the driver can be improved.
Preferably, the minimum cornering portion of the vehicle is an inner rear wheel, the maximum cornering portion of the vehicle is a front corner of an outer shape of the vehicle, the predicted path locus of the vehicle includes that of an outer rear wheel.
In this configuration, since the predicted path loci of both rear wheels and the maximum cornering portion are simultaneously displayed, a driver can discern the back-up direction and presence or absence of accessible space of the vehicle.
Preferably, the predicted loci are displayed in display formats in which they are distinguishable from each other.
In this configuration, since the predicted path loci of both rear wheels and the maximum cornering portion which are simultaneously displayed can be recognized individually according to their different display formats, they can be displayed with good visibility so that the predicted path loci of the rear wheels can be distinguishable from the maximum cornering portion.
Preferably, the display format is composed of a line type, a display color, a line width and a combination thereof. In this configuration, since the predicted path loci of both rear wheels and the maximum cornering portion are displayed in different display formats each composed of a line type, a display color, a line width and a combination thereof, a difference in the predicted path loci can be made clear and the driver can easily discern the difference.
Preferably, the predicted path locus of the maximum cornering portion has a turning radius computed from       R    ⁢          xe2x80x83        ⁢    max    =      "LeftBracketingBar"                  (                              Rout            2                    +                      L            2                          )              "RightBracketingBar"  
where Rout: a turning radius of an outer rear wheel when a vehicle is backed up, L: a distance between a rear wheel shaft and a front corner of an outer shape of the vehicle.
In this configuration, the predicted path locus of the maximum cornering portion can be displayed using the computed turning radius.
The above and other objects and features of the present invention will be more apparent from the following description taken in conjunction with the accompanying drawings.